Often, in manufacturing use environment, it is desirable to provide a spray coating to a substrate (e.g., a vehicle panel) that tapers from full thickness to a reduced thickness (or zero thickness) over a certain distance along the substrate. For example, if the coating is only desired over a central portion of the entire surface of the substrate, the taper could gradually reduce the coating thickness near the edge of that coated area to avoid an abrupt vertical “step” or “cliff” along the substrate surface.
This tapering is currently done by laying out staggered layers of masking tape on the substrate. However, known masking tape edge taper techniques are only effective over relatively short taper lengths for single-pass coating. Any longer, more gradual, taper length requires multiple coating passes, with the tape layers being manually removed between layers of the coating process. This and other known masking techniques often cause defects in coatings and are relatively labor intensive to use in manufacturing due at least to the precise tape positioning (sometimes difficult to reproduce with known flexible tape products) and the regimented removal required for all but relatively short taper lengths. Currently used shadow masking techniques also can cause a “dry spray” defect and/or an undesirably “stepped” aspect to the tapered areas of coating.